Recently bought a 2002 Grand Am. Dealer put 4 new tires on The day after I bought. The day after that the ABS, Service engine,trac lights all came on.had hubs checked they are fine.

it might be that the dealership put to large or to small of tires on the car and the calibration is off. the hubs are reading a different speed then the computer is reading from the speed sensor in the trans. call a tire company and see what size tires fit on the car and then call the dealership and tell them the problem and have them look at it. if the problem happened after they put on the tires they should check it for free and if the calibration is off they should either replace the tires with the right size or calibrate the computer. this is what might have happened but please dont hold me to it

Thanks for the quick answer. I will admit I'm fairly naïve when it comes to this. The factory specs are 225/50R15. They put on 205/50R15...the place I took it to for the hub check said the speed sensor seems accurate...they took it for a spin the diagnostic thing plugged in. Can that (what I would think is difference in size cause this? Thanks in advance...and sorry if these are stupid questions :)

Not sure if you have the 2002 Grand AM GT Coupe or Sedan, but the good news is that the OEM tire size is the same: 225/50R-16 (if the Dealer put on any other size than this, this could account for the issues you're having). Check what's on there and let us know. Here's a link with the OEM tire info from Tire Rack.com: http://www.tirerack.com/tires/SelectTireSize.jsp?autoMake=Pontiac&autoModel=Grand+Am+GT+Coupe&autoYear=2002&autoModClar=

Wait what?? 225/50R15??

here is what you have in the first is the 225/50R15 and the next is the 205 20 mph 19.3 30 mph 29 40 mph 38.7 50 mph 48.3 60 mph 58 70 mph 67.7 80 mph 77.3 90 mph 87 there isnt much of a change here but might be enough to throw some thing off. I would still go back to the dealer tell them the problem that you are having and see if they can swap you out with the right size tires for the car.